The present invention relates generally to the field of reinforcing bar (“rebar”) positioners, and more particularly, to a rebar positioner intended for use with a relatively new type of concrete masonry unit block manufactured and sold under the trademark ProBlock, and a method for utilizing such rebar positioners. Whereas conventional masonry blocks have two or more closed cores separated by a web, as shown in FIGS. 3, 4 and 5, the ProBlock blocks “B” have a single closed core “CC” and an open core “OC” between two face shells “S1” and “S2” separated by a web “W”. These blocks are manufactured in 8 inch and 12 inch widths, with variations to accommodate building and code requirements. Stated advantages of this design include lighter weight and the ability to position the blocks around vertically-positioned rebar extending up through a course of blocks without the need to lift the block over the top of the rebar to position it within the positioner, as is the case with closed core blocks. As used in this application, the term “open core” means that the core is defined by only three vertical walls, leaving one side of the core defined by the height of the block “open”.
It is common in masonry block construction to position rebar vertically within the core of a concrete block or other masonry block unit to provide added strength and stability to the masonry structure. In general, rebar will be used in selected cores, for example 24″ on center, that are filled with grout to anchor the rebar in its reinforcing position. Generally, it is desirable to have the rebar positioned at or proximate the center of the block core to maximize the stabilizing effect of the rebar. As such, a positioner is often used to maintain the rebar at the desired position within the block core while grout, concrete or other hardening fill material is poured into the block core.
Prior art rebar positioners typically include brackets with a closed or nearly closed ring-like area within which the rebar is positioned, and opposing members that extend perpendicularly over the block core onto the top surface of the block. Many of these prior art rebar positioners are constructed such that they lie entirely in one plane, and as such they extend over the top of the core block. Therefore, positioners must rely on the next masonry block being positioned on top of it to maintain its proper position, and the positioners are easily disturbed by movement of the overlying block. The perpendicular arrangement of the positioners contributes to their susceptibility to falling out of position. If the rebars are not maintained in their proper position, the strength and stability of the masonry structure is compromised.
To overcome the disadvantages of the prior art rebar positioner designs, U.S. Pat. No. 8,122,675 discloses and claims a continuous length of wire bent to provide a geometry that spans the corresponding diagonal length of the core of the block, seats only end portions of the positioner in the plane of the surface of the block, positions the rebar maintaining portions down within the core, and includes a telltale for indicating proper installation of the positioner within the core to ensure alignment of the rebar along the longitudinal axis of the block.
The development of the ProBlock style of masonry block with the open core suggests a different approach since the open cores do not support the type of positioner disclosed in the U.S. Pat. No. 8,122,675.